Abstract:
Introduction:
Post-operative pyrexia is a common cause of concern for both
surgeon and patient. The current study was performed in
order to assess the significance of this common symptom and the
need for prolonged hospitalization and diagnostic work-up in
such patients.
Methods:
We conducted a retrospective analysis of 77 consecutive joint arthoplasties performed at our institute. In all cases,
office notes indicate lack of a surgical site infection for a
minimum of two years. Demographic parameters, type of
anesthesia, blood loss and transfusion requirements as well as
leukocyte counts, urine cultures and chest radiographs were
correlated to temperature measurements. A febrile response
was considered oral temperature of more than 38 degrees Celsius.
Results:
58% of patients had a febrile response. This most commonly
occurred on the first and second post-operative days. The
febrile response was not correlated to amount of blood loss,
homologous transfusion, positive urine cultures or leukocytosis.
However, general anesthesia appears to be associated with a
febrile response perhaps due to pulmonary complications.
Conclusions:
A febrile response in the peri-operative arthroplasty patient
does not indicate a surgical site infection. It might be
related to the use of general anesthesia with some attendant
pulmonary damage. Hospital discharge should not be delayed
due to peri-operative pyrexia.
J.Orthopaedics 2007;4(3)e15
Keywords:
arthroplasty, pyrexia, inflammation, knee, hip,
peri-operative.
Background:
Postoperative
pyrexia in patients undergoing total joint arthroplasty
procedure is often alarming for both staff and patients.
Current surgical practice is to delay discharge of such
patients until they are afebrile for at least two days.
This is a wasteful practice, which is especially
difficult to accept in today's cost-conscious day and age.
The current study was conducted in order to assess the
significance of post-operative fever.
Furthermore, an attempt to define the variables
responsible for pyrexia has been made.
Based on results of this study, a treatment algorithm for
the patient with peri-operative post-arthroplasty fever is
suggested.
Material and Methods :
The
medical records of 77 consecutive patients were evaluated.
Pyrexia was defined as a temperature higher than 38
degrees Celsius. The
variables of concomitant diseases, pre-operative and
post-operative hemoglobin, amount of drained blood,
pre-operative and post-operative white blood cell count, amount
of transfused blood, results of urine cultures and results of
chest radiographs were evaluated.
Daily Q 4 hour measurements of oral temperature were made
using a digital thermometer accurate to one tenth of a degree
Celsius. The day of
surgery started in the recovery room and continued until
6:00 AM
on the following day.
Postoperative
Day one began at
6:00 AM
on the day after surgery and continued for 24 hours. Subsequent
postoperative days began and ended at
6:00 AM
in a repeating sequence. All patients in this series received
subcutaneous enoxaparin 40mg for six weeks.
All received peri-operative antibiotics (cefonicide – a
second generation cephalosporin) as a single pre-operative dose.
The use of incentive spirometers was encouraged in all
patients. All
patients began formal physical therapy and gait training on
postoperative day one. Patients
were hospitalized for 4 to 8 days (average hospitalization was
5.2±3 days).
The
procedures were performed in one university hospital during an 8
months interval. All
were primary replacement procedures.
All
patients had hospital records documenting a minimum of 2 years
post-operative follow-up without evidence of prosthetic joint
infection. No attempt was made to define clinical outcome
parameters other than the absence of peri-operative infection.
No
surgery was done if the patient had known pre-operative
intercurrent infection. Patients with immuno-compromising
disease or receiving immuno-suppressive drugs were excluded
(diabetic patients were not excluded).
Demographic
characteristics of the patients are recorded in Table 1.
To define variables that may have etiologic significance
relative to postoperative elevated temperatures, multiple
subgroups were examined within the combined populations of
patients who had total knee or hip replacements. Comparative
groups included:
Patients
who had a total knee replacement versus patients who had a total
hip replacement; patients who had a general anesthetic versus
patients who had epidural anesthesia; patients who received no
blood transfusion (at our institute only allogeneic blood is
transfused) versus patient who received blood; patients with
positive results of a urine culture versus patients with
negative results of a urine culture; as well as patients with an
abnormal chest radiograph versus patients without an abnormal
chest radiograph.
This
was a retrospective patient data analysis and thus informed
consent had not been obtained.
The institutional Ethical Review Board approved the
study.
Statistical
Analysis was performed using the Analyze-It add-in to Microsoft
Excel XP (Analyze-It Ltd., version 1.71, 2003).
Results :
58%
of patients had oral temperatures higher than 38 degrees Celsius
measured during their hospitalization.
Most commonly this occurred during the second
postoperative day. Maximal
temperature is similar in total knee arthroplasties (38.1+0.5)
as compared to total hip arthroplasty (38.0±0.5, t-test,
p>0.6). Average
daily temperature was also similar in both of these groups.
Leukocytosis
was not associated with elevated temperature (Pearson
correlation, r-value 0.06, p>0.7) or with abnormal chest
radiographs (1-way between subjects ANOVA, F-value=0.6,
p>0.6) or with positive urine cultures radiographs (1-way
between subjects ANOVA, F-value=0.3, p>0.7).
There was no correlation between temperature and amount
of blood drained from the wound (Pearson correlation, r-value
0.04, p>0.7).
Type
of anesthesia influences the maximal temperature recorded.
Patients undergoing general anesthesia had significantly
higher maximal temperature (38.3±0.5) than those undergoing
spinal anesthesia (38.1±0.4, t-test, p<0.05).
General anesthesia was associated as well with a
significantly larger decline in hemoglobin (9.3±1.3 gram per
deciliter) as compared to spinal anesthesia (10±1.2 gram per
deciliter, t-test, p<0.05).
Hemoglobin values remained significantly lower at
discharge in patients undergoing general anesthesia
(10.1±0.9 gram per deciliter) as compared to patients
undergoing spinal anesthesia (10.6±1, t-test, p<0.03).
Fifteen
patients (19%) were transfused.
Their maximal as well as their average temperature was
similar to that of those patients who were not transfused
(t-test, p>0.12). Transfusion
did not appear to be associated with leukocytosis (t-test,
p>0.09).
Forty
patients (51%) had urine cultures performed due to temperature
elevation. There was
a significant difference in temperature between those patients
in whom urine cultures were not performed (maximal temperature
38±0.4) then in these patients in whom cultures were performed
(38.3±0.5). However
there was no significant difference between those patients in
whom cultures were performed whatever the culture results
(ANOVA, F-value 2.9, p<0.05, Dunnet 95% confidence interval,
difference was 0.03).
Chest radiographs were performed in 26 patients (36%) due
to clinical findings during physical examination.
A positive chest radiograph was significantly associated
with elevated temperature (ANOVA, F-value 11.6, p<0.001, the
difference between patients that had an abnormal chest
radiograph and those that did not have a radiograph was
significant, Dunnet 95% confidence).
Six patients had blood cultures due to elevated
temperature. All
blood cultures were negative.
The
type of anesthesia appears to predispose to pyrexia, i.e.
general anesthesia is related to post-operative pyrexia (1-way
between subjects ANOVA, F-statistic=3.8, p<0.05), perhaps due
to pulmonary complications as evidenced by abnormal chest
radiographs (Kruskal-Wallis ANOVA, KW Statistic=24.6,
p<0.001).
Urine
cultures are quite often positive in the post-arthroplasty
patient, perhaps due to their average age and debilitation.
However, no statistically significant correlation is
found between the presence of positive urine culture and
postoperative pyrexia (Kruskal-Wallis ANOVA, KW statistic 3.5,
p>0.05).
Discussion :
The
study appears to indicate that pyrexia occurs in the majority of
patients following lower limb arthroplasty.
This finding is probably attributable to an inflammatory
response of the body to the surgical insult, which occurs fairly
uniformly after hip operations [1]. There does not appear to be
any correlation between elevated temperatures after knee or hip
arthroplasty and infection of the surgical site.
According to the current study, there is no correlation
between positive urine cultures and post-operative pyrexia.
This finding concurs with that of Shaw et al. who have
found no relationship between pyrexia and a positive urine
culture [2]. In another study, patients with positive urine
cultures uniformly did not have pyrexia [3]. However, a positive
chest radiograph appears to be correlated with elevated
temperatures. This
probably means that patients with elevated temperatures and
abnormal pulmonary physical findings are likely to have an
abnormal finding on chest radiographs.
However, many of these findings are non-specific and do
not necessarily indicate a cause and effect relationship to the
pyrexia.
There
was no relation between pyrexia and bleeding-related parameters
(including amount of blood lost, blood transfusion or
pre-hospitalization or pre-discharge hemoglobin, ANOVA).
Kennedy et al [3] reported a weak correlation that did
not reach statistical significance between perioperative blood
loss and pyrexia in a series of 92 consecutive TKA.
In our series no such correlation was observed.
This
finding is similar to what has been reported by Kennedy et al
[3] but contrasts with the observation reported by Guinn and
colleagues that urine analysis might explain some cases of
post-operative pyrexia [4].
What
is the reason for the pyrexia?
The relationship to general anesthesia might indicate
that pulmonary dysfunction or perhaps infective agents
introduced into the pulmonary system are involved.
However, it has been shown that an intense inflammatory
response occurs after lower limb arthroplasties due to cytokine
secretion. A major
cause might be interleukin-6, whose level is increased following
lower limb arthroplasty, and has been shown to be responsible
for febrile reactions in the post-arthroplasty patient [5].
Another factor might be the formation of
platelet-leukocytes complexes concomitantly with interleukin-6
secretion, which occurs after arthroplasty, lasts for about two
weeks and is responsible for an inflammatory response as well as
activation of the thrombotic mechanism [6].
The
current study appears to indicate that post-operative pyrexia
after lower limb arthroplasty is not a cause for concern from
the perspective of possible surgical site infection, but rather
a normal expected finding. There
does not appear to be any reason to delay discharge of patients
due to pyrexia without localizing physical findings.
However, the inflammatory response accompanying
arthroplasty is important as increased interleukin-6 levels are
associated with delayed functional rehabilitation
post-operatively [7]. Thus, it appears of importance to include
a mechanism for decreasing the inflammatory response
post-arthroplasty, in rehabilitation protocol of arthroplasty
patients.
|
Total Hip Arthroplasty N=47
|
Total Knee Arthoplasty N=30
|
Statistical Significance
|
Diagnosis
|
Osteoarthritis 35
Aseptic Necrosis 10
Rheumatoid arthritis 2
|
Osteoarthritis 25
Aseptic Necrosis 2
Rheumatoid arthritis 3
|
Unsuitable numbers to compare
|
Age
|
68.1±3
|
68.5±4
|
t-test = 0.2, 2-tailed p>0.8
|
Diabetes mellitus
|
11 patients
|
8 patients
|
Mann-Whitney U statistic 713, p>0.9
|
Ischemic Heart Disease
|
8 patients
|
6 patients
|
Mann-Whitney U statistic 711, p>0.9
|
Hypertension
|
13 patients
|
9 patients
|
Mann-Whitney U statistic 723, p>0.8
|
Febrile response
|
28 patients
|
17 patients
|
Mann-Whitney U statistic 684, p>0.8
|
Table 1: Demographic
Characteristics of Patients included in the Study
A cut-off value of p<0.05 was considered as significant.
T-test for independent samples (two-tailed) was used for
contiuous variables. Mann-Whitney test or Kruskal Wallis
were used for nominal variables.
Reference :
-
Okafor B, MacLellan G: Postoperative changes of erythrocyte
sedimentation rate, plasma viscosity and C-reactive protein
levels after hip surgery. Acta Orthop Belg 1998,
64:52-56.
-
Shaw
JA, Chung R: Febrile response after knee and hip arthroplasty. Clin
Orthop Relat Res 1999, 367:181-189.
-
Kennedy
JG, Rodgers WB, Zurakowski D, Sullivan R, Griffin D, Beardsley
W, et al: Pyrexia after total knee replacement. A cause for
concern? Am J Orthop 1997, 26:549-552, 554.
-
Guinn S, Castro FP, Jr, Garcia R, Barrack RL: Fever following
total knee arthroplasty. Am J Knee Surg 1999, 12:161-164.
-
Handel
M, Winkler J, Hornlein RF, Northoff H, Heeg P, Teschner M, et
al: Increased interleukin-6 in collected drainage blood after
total knee arthroplasty: an association with febrile reactions
during retransfusion. Acta Orthop Scand 2001, 72:270-272.
-
Bunescu
A, Widman J, Lenkei R, Menyes P, Levin K, Egberg N: Increases in
circulating levels of monocyte-platelet and neutrophil-platelet
complexes following hip arthroplasty. Clin Sci (Lond)
2002, 102:279-286.
-
Hall
GM, Peerbhoy D, Shenkin A, Parker CJ, Salmon P: Relationship of
the functional recovery after hip arthroplasty to the
neuroendocrine and inflammatory responses. Br J Anaesth
2001, 87:537-542.
|